you need to be level 20 or higher to play them.
you can buy them from the merchant that sells maps in town. they are named Epic bossmaps. there's a boss map for each type of tileset in the game.
to install the mod just extract the mod to %appdata%\runic games\torchlight\mods
if they don't show up at first, try to go to the main dungeon and back to town and try again.
Warning! the maps are filled with bosses proceed at your own risk.
here is the download:
http://dl.getdropbox.com/u/1016238/torchlight%20mods/EpicBossMaps.zip
mirrors:
torchlight insider
RGF
megaupload
also available in Torchleech
if anyone wants a lighter version you can download it here
http://dl.dropbox.com/u/1016238/torchlight%20mods/lightBossMaps.zip
it's about half of the boss monsters (75-150 boss monsters instead of the normal 200-400)
and reduces the normal monsters


